Experimental characterization of deformation, coefficient of earth pressure at rest, stiffness, and contact force distributions of sand during secondary compression and rebound
Bibliographic record
Abstract
This paper aims to provide a comprehensive picture of the sand responses during secondary compression and rebound based on experimental characterizations. The experiment was carried out on dry Leighton Buzzard sand using a modified direct shear box equipped with tactile pressure sensors for the stress measurements and bender elements for stiffness (i.e., Ghv and Ghh) monitoring. It was found that secondary compression and rebound followed the same deformation trends as primary compression and rebound to continuously contract and expand, respectively. The deformation characteristics determined the changes in the associated soil properties; therefore, the opposite soil behavior during secondary compression and rebound was observed. During secondary compression, the corresponding void change, deviatoric strains εq, and the deviatoric strain rate [Formula: see text] increased with increasing vertical stress [Formula: see text] or deviatoric stress q because the sample crept more easily under a higher [Formula: see text] or q. The compression deformation gave rise to an increase in the horizontal stress [Formula: see text] and associated coefficient of earth pressure at rest K0. The soil stiffness also increased as the contact normal forces became more homogenized. During secondary rebound, the sample expanded unabated no matter whether [Formula: see text] was greater or smaller than [Formula: see text]. The corresponding void ratio change, εq, and [Formula: see text] increased with decreasing [Formula: see text] or q because the sample expanded more easily under a lower [Formula: see text] or q. The expansion gradually reduced [Formula: see text] along with the associated K0 value. The sample stiffness continued to decrease, and contact force homogenization was not observed.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".